Poplar Island: Understanding the Development of a Beneficial Use Restoration Site

This article was prepared by a U.S. government employee as part of the employee's official duties and is in the public domain in the United States.

Historically, the Chesapeake Bay contained numerous islands (Wray et al. 1995, Cronin 2005) providing valuable habitat to breeding waterbirds due to reduced levels of mammalian predation and human conflict, relative to mainland sites (Erwin et al. 2001, Duerr and Watts 2012, Vitale et al. 2020). However, this watershed has seen dramatic losses in island habitat since the 1800s driven by erosion and sea level rise (Leatherman et al. 1995, Cronin 2005, Marbán et al. 2019). This loss of habitat has had marked effects on regional waterbird populations, with declines in numerous species including several identified as species of concern in Maryland and Virginia (Brinker et al. 2007, Williams et al. 2007, Erwin et al 2011). A prime example of the loss of remote island habitat in the Chesapeake Bay is Poplar Island, a site that was once a natural remote island offshore of Tilghman Island, Maryland in the main stem of the Chesapeake Bay. Poplar Island is perhaps best known for its storied history as habitat for migratory waterfowl, which were so prevalent that it became a hunting retreat for prominent figures including Theodore Roosevelt (Eshelman and Russel 2004). Despite its prominence, Poplar Island fell victim to the same forces of sea level rise and erosion that have impacted islands throughout the Chesapeake Bay, decreasing from a length of approximately four miles and a total of 460 hectares in 1847 to its nadir of 1.5 hectares in the early 1990s (MES 2017).

The U.S. Army Corps of Engineers (USACE) and the Maryland Department of Transportation Maryland Port Administration (MDOT MPA) recognized the loss of islands as a unique opportunity to address a long-standing issue with dredge material produced during maintenance of shipping channels for the Port of Baltimore (Anderson-Austra et al. 1996). While port operation requires shipping channels to be dredged annually to ensure safe passage of vessels, the storage of dredge spoils can be expensive and controversial (Maher et al. 2013). However, this same material can be used to restore remote island habitat under a "beneficial use" concept, addressing habitat loss and dredge disposal concerns at once (Burt 1996). As a result, the Poplar Island Project Team was formed in 1994 to reconstruct Poplar Island to its 1847 footprint. Containment dikes were constructed to hold the dredged material in 1998, and dredge deposition began in 2001 with construction ongoing ever since. The first wetland cell was completed in 2003 via the planting of high marsh dominated by Spartina patens and low marsh dominated by Spartina alterniflora (GBA 2003), a composition generally replicated in subsequent developed marsh cells. While the project has numerous goals such as efficient dredge material placement, habitat management has been focused on development of a diversity of habitats for native flora and fauna (MES 2021).

While there have been several other beneficial use projects focused on restoring island habitat (e.g., Schreiber and Schreiber 1978, Yozzo et al. 2004), Poplar Island is one of the largest and most complex. Despite the numerous challenges presented by a project of this scale, the restoration of Poplar Island has been a success, addressing both the economic and environmental issues identified at this project's inception. As of January 2021, this project has enabled the deposition of 37.1 million cubic yards (mcy) of dredge material (MES 2021), with plans to deposit a total of 68 mcy by 2032. Beyond the economic impacts inherent in facilitating continued operation of a major regional port (Martin Associates 2018), the restoration of Polar Island has had demonstrable benefits to wildlife populations. For instance, monitoring efforts have indicated that a diverse avian assemblage consistently uses Poplar for nesting or stopover habitat, with over 220 species observed on site and more than 30 species confirmed to have bred on Poplar Island since...